Quantum state detection efficiency relies on the efficiency of the collection of light fluorescence from optical systems. Fluorescent light collection may, for example, be implemented with bulk optics.
For instance, fluorescent light collection may involve placing a high numerical aperture objective near a fluorescence point source (e.g., an atomic ion) and detecting emitted fluorescent light (e.g., photons) outside of a vacuum chamber, whereby the detection may be several inches away. Such a setup may yield a solid angle capture for emitted fluorescent light, for example, of less than 5%.
Collection of fluorescent light using bulk optics may involve careful alignment of optical and other elements (e.g., lasers, lenses, ion traps, etc.). Without this careful alignment, much of the fluorescent light may be lost, thereby contributing to a decrease in quantum state detection efficiency. The use of bulk optical elements also may adversely affect robustness (e.g., to wear, impact, etc.) of a quantum informatics system, possibly limiting use of such systems to research environments.